Multi-ply collapsible bulk container

ABSTRACT

A bulk container is disclosed, having a plurality of substantially planar walls, a plurality of corners connecting the walls, and a top and a bottom both formed by a plurality of foldable flaps. A first corner and a second corner opposite the first corner each have two substantially parallel score lines on an inner side of each corner allowing the corners to fold at an angle of substantially 0° while maintaining the structural integrity of the container. The walls of the container are constructed from a multi-ply corrugated cardboard sleeve made up of two layers of multi-ply corrugated cardboard laminated to each other. Two corrugated cardboard inserts, each having foldable top and bottom flaps are laminated to the sleeve. Also disclosed is a method of manufacturing the container using a number of blanks and inserts.

TECHNICAL FIELD

The invention relates generally to a bulk container, and morespecifically to a collapsible cardboard container adapted to hold aflowable substance contained in a bag.

BACKGROUND OF THE INVENTION

Large bulk containers are often formed from a generally rectangularblank, usually flat, which has been suitably scored and crushed, byfolding certain panels of the blank and then joining the ends of theblank to form a flattened tube structure. After the formation of theblank into a collapsed tube by joining its opposite ends, the packageror final user of the bulk container then unfolds or erects the flattenedtube structure into its expanded, tubular condition or configuration, tothereby form a bulk container of generally rectangular configuration.Along those portions of the bulk container which are to be folded to a0° angle (often termed a reverse fold) in passing from the original,planar blank to the collapsed or knocked down tube, there is, in priorart bulk containers of this type, often significant damage to thestructural integrity of the container. The most common such damage is adistortion and tearing caused by compression and/or tension of thepaperboard material at these vertically extending edges of the bulkcontainer, where the 0° folds become 90° folds or edges upon refolding90° attendant set-up or erection. The strength of the erected containeris diminished by this damage and the appearance of the container atthese folds is also marred.

Increasing the thickness of a container wall increases the compressive,tensile, and shear strength of the wall. Thus, it is desirable to designa container in which walls of greater thickness can be used. However,thicker walls experience greater stresses at the fold lines,particularly when folded to angles approaching 0°. Scoring or crushingcorners are known methods to ease the pressure created at a fold line,but prior scoring arrangements and methods have drawbacks. Some areeffective only on walls of certain limited thickness. Other designs donot fold tightly, leaving space on the inside of the collapsed containerand, more importantly, creating bulges in the material near the reversefold line. Thus, there exists a need for a container having walls ofgreat thickness that are able to be easily folded flat to an angle of 0°without damage to the structural integrity of the container.

The present invention is provided to solve the problems discussed aboveand other problems, and to provide advantages and aspects not providedby prior bulk containers of this type. A full discussion of the featuresand advantages of the present invention is deferred to the followingdetailed description, which proceeds with reference to the accompanyingdrawings.

SUMMARY OF THE INVENTION

The present invention provides a bulk container having a plurality ofsubstantially planar walls, a plurality of corners connecting the walls,and a top and a bottom both formed by a plurality of foldable flaps. Afirst corner and a second corner opposite the first corner each have twosubstantially parallel score lines on an inner side of each cornerallowing the corners to fold at an angle of substantially 0° whilemaintaining the structural integrity of the container.

In one embodiment, the walls of the container are formed of at least twothree-ply corrugated cardboard blanks and at least two two-plycorrugated cardboard inserts, wherein the inserts do not overlap eachother. In another embodiment, the walls are formed of two additionalthree-ply corrugated cardboard blanks. In another embodiment, the wallsare formed of at least eight-ply corrugated cardboard sheet. In anotherembodiment, a third inner corner and a fourth inner corner each have ascore line allowing each of the third and fourth corners to fold at anangle of at least 90° while maintaining the structural integrity of thecontainer.

In one embodiment, the inserts are located on an interior of thecontainer. In another embodiment, the inserts are located on an exteriorof the container.

The present invention also provides a bulk container constructed from amulti-ply corrugated cardboard sleeve made up of two layers of multi-plycorrugated cardboard laminated to each other. The sleeve is folded toform a plurality of walls and a plurality of corners defining theperimeter of the container. Two corrugated cardboard inserts, eachhaving a foldable top flap and a foldable bottom flap, are laminated toa surface of the sleeve, with each insert extending approximately halfthe perimeter.

In one embodiment, a first corner and a second corner opposite the firstcorner each have two substantially parallel score lines on an inner sideallowing the first and second corners to fold at an angle ofsubstantially 0° while maintaining the structural integrity of thecontainer. In another embodiment, a third corner and a fourth cornereach have a score line allowing each of the third corner and the fourthcorner to fold at an angle of at least 90° while maintaining thestructural integrity of the container.

In one embodiment, the inserts are laminated to an interior surface ofthe sleeve. In another embodiment, the inserts are laminated to anexterior surface of the sleeve.

The present invention also provides a method of constructing a bulkcontainer having a top, a bottom, and a plurality of walls. In thismethod, two cardboard blanks are provided, each having two panelsseparated by a fold line created by a pair of substantially parallelscore lines. An insert is also provided, having a top flap, a bottomflap, and two panels separated by a fold line. First, a surface of thefirst blank is attached to a surface of the second blank so that thefold line of the first blank is substantially aligned with the fold lineof the second blank. Next, a surface of the insert is attached to asurface of the second blank such that one panel of the insert issubstantially aligned with one panel of the second blank. Finally, theblanks and the insert are folded at the fold lines to create a number ofthe walls of the bulk container.

In one embodiment, two additional blanks are provided, each having twopanels separated by a fold line created by a pair of substantiallyparallel score lines. A second insert is also provided, having a topflap, a bottom flap, and two panels separated by a fold line. In thisembodiment, a surface of the third blank is attached to a surface of thefourth blank such that the fold line of the third blank is substantiallyaligned with the fold line of the fourth blank. Then, a surface of thesecond insert is attached to a surface of the fourth blank such that onepanel of the second insert is substantially aligned with one panel ofthe fourth blank. Next, these additional blanks and inserts are foldedat the fold lines to create a number of the walls of the bulk container.Finally, the two container portions are attached to each other to createfour walls and four substantially 90° corners of the bulk container.

In another embodiment, the first blank also has a third panel, separatedfrom the second panel by a second fold line created by a score line, anda fourth panel, separated from the third panel by a third fold linecreated by a pair of substantially parallel score lines, and the secondblank also has a third panel, separated from the second panel by asecond fold line created by a score line, and a fourth panel, separatedfrom the third panel by a third fold line created by a pair ofsubstantially parallel score lines. A second insert is also provided,having a top flap, a bottom flap, and two panels separated by a foldline. In this embodiment, a surface of the first blank is attached to asurface of the second blank such that the fold lines of each blank aresubstantially aligned with those of the other blank. Next, a surface ofthe second insert is attached to a surface of the second blank such thatone panel of the second insert is substantially aligned with one panelof the second blank. Finally, the blanks and inserts are folded at thefold lines to create four walls and four substantially 90° corners ofthe bulk container.

In another embodiment, the pair of substantially parallel score linesallow the first blank and the second blank to fold at substantially a180° angle while maintaining the structural integrity of the container.In another embodiment, the blanks are each constructed of three-plycorrugated cardboard, and the insert is constructed of two-plycorrugated cardboard. In another embodiment, one blank further comprisesa second fold line creating a connecting flap, and the blanks areattached in an offset manner, allowing the connecting flap to fold atthe second fold line. In another embodiment, the insert and the blanksare folded such that the first insert is located on an exterior of thebulk container. In another embodiment, the insert and the blanks areattached by laminating with an adhesive.

BRIEF DESCRIPTION OF THE DRAWINGS

To understand the present invention, it will now be described by way ofexample, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a collapsible bulk container having aclosed top;

FIG. 2 is a side elevation view of the container of FIG. 1;

FIG. 3 is a perspective view of the container of FIG. 1 having an opentop;

FIG. 4 is a cross-section view of the container of FIGS. 1-3, takenalong line 4-4 of FIG. 3;

FIG. 5 is an isometric view of the container of FIG. 1 in a collapsedstate;

FIG. 6 is a cross-section view of the box of FIG. 4 in a partiallycollapsed state;

FIG. 7 is a plan view of an insert for use in constructing a collapsiblebulk container;

FIG. 8 is a schematic view of a step in a method of manufacturing acollapsible bulk container using a first blank having four fold linesand a similar blank having three fold lines;

FIG. 9 is a plan view of the first blank of FIG. 8, having four foldlines;

FIG. 10 is a schematic view of a step in the method of manufacturing acollapsible bulk container, using the insert of FIG. 7, the blanks ofFIG. 8;

FIG. 11 is a plan view of the container of FIG. 1 in a collapsed state;

FIG. 12 is a magnified cross-sectional view of a corner of the collapsedcontainer of FIG. 5;

FIG. 13 is an isometric view of the container of FIG. 1, having an outerlayer partially peeled away to illustrate the connection between thelayers;

FIG. 14 is a perspective view of a second embodiment of a collapsiblebulk container having a closed top;

FIG. 15 is a cross-section view of the container of FIG. 14, taken alongline 15-15 of FIG. 14;

FIG. 16 is an isometric view of the container of FIG. 14 in a collapsedstate;

FIG. 17 is a magnified cross-sectional view of a corner of the collapsedcontainer of FIG. 16;

FIG. 18 is an isometric view of the container of FIG. 14, having aninsert partially peeled away to illustrate the connection between thelayers;

FIG. 19 is a schematic view of a step in a second embodiment of a methodof manufacturing a collapsible bulk container using two blanks havingtwo fold lines each and two blanks having a single fold line each;

FIG. 20 is a plan view of one blank of FIG. 19 having two fold lines andone blank of FIG. 19 having a single fold line; and

FIG. 21 is a schematic view of a step in the method of manufacturing acollapsible bulk container shown in FIG. 19, using the blanks of FIG. 20and an insert similar to the insert of FIG. 7.

DETAILED DESCRIPTION

While this invention is susceptible of embodiments in many differentforms, there are shown in the drawings and will herein be described indetail preferred embodiments of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to the embodiments illustrated.

Referring now to FIGS. 1-21, and initially to FIGS. 1 and 14, there isshown a bulk container 10 having four substantially planar walls 12 andfour corners 28, each corner 28 connecting two walls 12, a top 16 formedby four foldable flaps 20, and a bottom 18 formed by four foldable flaps20. A preferred embodiment is depicted in FIGS. 1-13, and the mostpreferred embodiment is depicted in FIGS. 14-21. The walls 12 of thecontainer 10 are formed of a sheet material, preferably cardboard. Asshown in FIGS. 1 and 14, the container 10 is rectangular, havingbi-lateral symmetry (i.e., not square). However, in another embodiment,the container 10 is square. In still further embodiments, the container10 has a larger or smaller number of walls 12 and corners 28, and oneskilled in the art would recognize how to design the container 10accordingly. The container 10 disclosed is particularly useful forholding a storage bag (not shown) for holding a flowable substance,preferably a storage bag contained in a foldable cardboard cartridge(not shown). In the container 10 shown in FIGS. 1 and 14, the top 16does not completely enclose the interior, leaving a space 22 to allowfor filling the bag inside with liquid or another flowable substance.The bottom 18 is similarly constructed, but the space 23 in the bottom18 is preferably covered by the cardboard cartridge as the bag isfilled. Alternately, the top 16 and/or the bottom 18 can be designed toclose completely. Additionally, the container 10 has a drain hole 24near the bottom of one of the walls 12 to accommodate a drainage spout(not shown) near the bottom of the inner bag. Preferably, the container10 is collapsible so that it is nearly or completely flat, asillustrated in FIGS. 5-6 and 11. As described below, score lines at thecorners 28 of the container 10 facilitate collapsing of the container10.

Two of the corners 28 each have two substantially parallel score lines26, which are preferably spaced 2⅝″ apart in the embodiment shown inFIGS. 1-13 and 2¼″ apart in the embodiment shown in FIGS. 14-21. Thesedouble-scored corners are indicated by “DS” generally in the FIGS. Asshown in FIGS. 12 and 17, the double-scored corners 28 can be folded atan angle of substantially 0°, with little free space remaining.Additionally, the structural integrity of the container 10 is maintaineddue to the presence of the two score lines 26, and there is little or nocrushing, tearing, bulging, distortion, or other permanent damage doneto the container 10 by folding at such a sharp angle. In other words,the two score lines 26 allow their respective corners 28 to fold at anangle of substantially 0° while maintaining the structural integrity ofthe container 10. The other two corners 28 each have a single score line26 allowing each of those corners 28 to fold at an angle of at least 90°while maintaining the structural integrity of the container 10, as shownin FIGS. 4 and 15. These single-scored corners are indicated by “SS”generally in the FIGS. Preferably, the two double-scored corners 28 arelocated opposite each other (i.e. diagonally), and the two single-scoredcorners 28 are located opposite each other as well, as shown in FIGS. 4and 15. This configuration permits the box to be collapsed into aflattened container 10, as shown in FIGS. 5-6. In the flattenedcontainer 10, the two double-scored corners 28 are folded at angles ofsubstantially 0°, and the two single scored corners 28 are unfolded(i.e. are at an angle of substantially 180°). In other embodiments,other scoring arrangements are used, and all corners 28 can besingle-scored or double-scored, or may not be scored at all.

In the preferred embodiments, the inner side of each corner 28 isscored, as illustrated in FIGS. 4 and 15. In other words, the innersurface 13 of the container 10 proximate each corner 28 is scored. Sincethe walls 12 of the container 10 are thick, scoring on the inside maynot be visible or detectable from the outside of the container 10. Thepreferred container 10 has relatively deep score lines 26 on the innersurface 13 of the container 10, extending through most of the thicknessof the walls 12 to create the greatest ease of folding.

As shown in FIGS. 12 and 17, the double-scored corners 28 fold tightlyand squarely to a 0° angle. Little, if any, discernable space is left onthe inside of the collapsed container 10. Further, the outside of thecollapsed corner 28 is squared, rather than rounded, and the surface ofthe collapsed container 10 is flat from edge to edge. This flatnessfacilitates stacking multiple flattened containers 10, because thecompleted stack will not wobble due to space between the edges of thecontainers 10.

Generally, the walls 12 of the container 10 are formed of a sheetmaterial, and are preferably constructed from at least two blanks 30,32(at least one inner blank 30 and at least one outer blank 32) and twoinserts 34, all made of a flexible sheet material. Preferably, theblanks 30,32 and inserts 34 are made from multi-ply corrugated cardboardlaminate. Most preferably, the walls 12 of the bulk container 10 areformed of eight-ply corrugated cardboard sheet, as shown in FIGS. 12 and17. In total, the eight-ply walls 12 are 1⅝″ thick in the preferredembodiment. In other embodiments, other sheet materials are used,including, without limitation, polymers, fiberglass, wood, metal, orcombinations thereof. In the eight-ply embodiment shown in FIG. 1, twothree-ply blanks 30,32 form the four walls 12 of the container 10, eachextending around the entire perimeter of the container 10, and twotwo-ply inserts 34 are laminated to the inside of the inner blank 30 sothat each goes half-way around the perimeter and does not overlap theother. In the most preferred embodiment, four three-ply blanks 30,32form the four walls 12 of the container 10, each extending half-wayaround the entire perimeter of the container 10 and overlapping oneanother, and two two-ply inserts 34 are laminated to the outside of theouter blanks 32 so that each goes half-way around the perimeter and doesnot overlap the other. In other embodiments, a different number ofblanks 30,32 and/or inserts 34 are used, and the blanks 30,32 andinserts 34 have different thicknesses.

The blanks 30,32 are preferably formed from multi-ply corrugatedcardboard laminate, most preferably from CAA triple-walled board. In theembodiment shown in FIGS. 1-13, the inner blank 30 and the outer blank32 are the same length, and have four panels 36 created by three foldlines 14, as shown in FIG. 9. Preferably, two of these fold lines 14 aredouble-scored and the third fold line 14 is single-scored and locatedbetween the two double-scored fold lines 14. As discussed herein, otherscoring arrangements are possible. In the embodiment shown in FIGS.14-21, the inner blanks 30 and the outer blanks 32 are the same length,and have two panels 36 created by a single fold line 14, as shown inFIGS. 19-20. Preferably, this fold line 14 is double-scored. In otherembodiments, the blanks 30,32 have a different number of panels 36 andfold lines 14, particularly if the blanks 30,32 are being used to createa container 10 having more than four sides 12. In still furtherembodiments, the number of panels 36 and fold lines 14 in the outerblanks 32 and the inner blanks 30 can differ. For example, one largeouter blank 32 and two or more smaller inner blanks 30 can be used.

Additionally, the outer blank 30 preferably has a small connecting flap38 created by an additional, single-scored fold line 14. In thepreferred embodiments, the inner blank 30 and outer blank 32 areattached so they are slightly offset from one another. In the assembledcontainer 10 shown in FIG. 13, the connecting flap 38 overlaps theopposite end 39 of the inner blank 30 to create more strength andstability in the seam. In the most preferred container 10, theconnecting flap 38 of one outer blank 32 overlaps a portion 39 of thesecond inner blank 30 when the container 10 is assembled, as shown inFIG. 19. In such arrangements, the score lines 26 of the inner 30 andouter blank 32 are also offset to ensure that the score lines 26 of theinner blank 30 are aligned with the score lines 26 of the outer blank32. In other embodiments, the blanks 30,32 are not offset and noconnecting flap 38 is present. In still further embodiments, the offsetis more exaggerated, and both blanks 30,32 have a foldable connectingflap 38.

The preferred inserts 34 incorporated in the present container 10 areall very similar to each other. Each insert 34 preferably has two panels36 created by a single fold line 14, which is single-scored, as shown inFIGS. 7 and 21. One panel 36 is preferably larger than the other, sincethe preferred container 10 is rectangular. In an alternate embodiment,the panels 36 are of equal size, particularly when the container 10 isshaped as a square or other regular polygon. In some embodiments, onlyone insert 34 is used, and in other embodiments, more than two inserts34 are used. In still other embodiments, the inserts 34 have a greateror smaller number of panels 36, particularly if the container 10 has adifferent number of walls 12, if a different number of inserts 34 areused, or if the inserts 34 overlap each other.

The top flaps 20 and the bottom flaps 20 are preferably formed byfoldable portions of the inserts 34, with each insert 34 having two topflaps 20 and two bottom flaps 20. Thus, the thickness of these flaps 20is smaller than the material of the rest of the container 10, allowingthe flaps 20 to be freely foldable without the use of scoring. However,in an alternate embodiment, the fold lines of the flaps 20 are scored.In further embodiments, the flaps 20 have a greater or smallerthickness. In the preferred embodiments, the top and bottom flaps 20 areidentical to each other. Each of the top flaps 20 has either two flanges40 or slots 42 to interlock with the respective slots 42 or flanges 40of the adjacent flaps 20 when the flaps 20 are folded inward. Onceinterlocked, these top flaps 20 form the top 16 of the container 10. Thebottom flaps 20 are similarly constructed to form the bottom 18 of thecontainer 10. The preferred inserts 34 have one flanged top flap 20, oneslotted top flap 20, one flanged bottom flap 20, and one slotted bottomflap 20. One skilled in the art would recognize that the orientation ofthe flaps 20 shown in FIG. 7 can be switched by flipping the insert 34over (i.e. 180°). Additionally, various means of interlocking orotherwise connecting flaps 20 to close the top 16 of a container 10 areknown and may be used. Further, in other embodiments, no top and/orbottom flaps 20 are present, and other means to close the container 10can be used. In still other embodiments, the top flaps 20 and bottomflaps 20 are very different from each other.

In the embodiment shown in FIGS. 1-13, the two inserts 34 used arepreferably identical to each other. Likewise, the inserts 34 used in theembodiment shown in FIGS. 14-21 are preferably identical to each other.However, the inserts 34 used in each of these embodiments differsslightly from those used in the other, as can be seen by observing FIGS.7 and 21. Primarily, the flaps 20 in FIG. 7 are more widely spaced nearthe fold line 14, but extend farther from the outer edge of the insert34, than the flaps 20 shown in FIG. 21.

When assembled, the inner blanks 30 are connected to the inner surfacesof the outer blanks 32, preferably by laminating with glue or otheradhesive 44. The connected inner 30 and outer blanks 32 form a sleeve46. Preferably, the inner blank(s) 30 form an inner layer 48 extendingcompletely around the perimeter of the container 10, and the outerblank(s) 32 form an outer layer 50 extending completely around theperimeter. All corners 28, as well as the shape of the container 10,are, therefore, preferably defined by the sleeve 46. In the preferredembodiments, the sleeve 46, as well as each layer 48,50, is made ofmulti-ply corrugated cardboard and defines the four corners 28 and therectangular perimeter of the container 10. Most preferably, the sleeve46 is made of six-ply corrugated cardboard, or two layers 48,50 ofthree-ply corrugated cardboard. In the preferred embodiments, the sleeve46 has two single-scored corners 28 and two double-scored corners 28, asdescribed above.

In the embodiment illustrated in FIGS. 1-13, both the inner 30 and outerblanks 32 extend around the perimeter of the container 10. Theconnecting flap 38 of the outer blank 32 overlaps the opposite end 39 ofthe inner blank 30 to form a secure connection, as shown in FIG. 13. Inthe embodiment shown in FIGS. 14-21, each blank 30,32 extends half-wayaround the perimeter of the container 10. Each inner-outer blank pair30,32 (as shown in FIG. 21) forms a half-container 11, which is attachedto another half-container 11 to form a full container 10. The connectingflap 38 of each half-container 11 overlaps a portion 39 of the innerblank 30 of the other half-container 11 to ensure strong connection. Ifa greater number of blanks 30,32 are used, each blank 30,32 will extendaround a smaller fraction of the perimeter.

The inserts 34 are connected to a surface of the sleeve 46, preferablyby laminating. In the embodiment shown in FIGS. 1-13, the two inserts 34are laminated to the inner surface of the sleeve 46. Conversely, in theembodiment shown in FIGS. 14-21, the two inserts 34 are laminated to theouter surface of the sleeve 46. Preferably, neither of the two inserts34 extends completely around the perimeter of the container 10 noroverlaps the other insert 34. In other embodiments, the inserts 34overlap each other, and can extend around the complete perimeter of thecontainer 10. In still other embodiments, adhesive is not used toconnect the blanks and inserts 34, and any suitable means of connectionknown in the art can be used. In the embodiment of FIGS. 1-13, the scoreline 26 of each insert 34 is aligned with the single-scored fold lines14 of the blanks 30,32. In the most preferred embodiment, the score line26 of each insert 34 is aligned with the single-scored fold line 14 ofeach outer blank 32, adjacent the connecting flap 38. The edges of theinner blanks 30 form a juncture in alignment with the single-scored foldline 14, so no additional scoring of the inner blank 30 is necessary.Since the fold lines 14 of the blanks 30,32 and inserts 34 are alignedin the assembled container 10, the panels 36 of the inserts 34 aredimensioned to be approximately the same size as the correspondingpanels 36 of the blanks 30,32. In this arrangement, each insert 34covers two panels 36 of the inner blank 30, extending substantially tothe double-scored fold lines 14, but not farther. Thus, the inserts 34leave the double-scored corners 28 of the container 10 uncovered, so asnot to interfere with the 0° fold, as illustrated in FIGS. 12 and 17. Inother embodiments, the inserts 34 cover the double-scored corners 28 andcan have double-scored fold lines. Further, if different blanks 30,32 orinserts 34 are used, the blanks and inserts 34 are connected in othermanners.

In the most preferred embodiment, the inserts 34 are on the outside ofthe container 10, as described above. Thus, the flaps 20 extend over theinner plies of the container 10 towards the center of the blank,covering the entire thickness of the container walls 12 and protectingtheir edges from damage, as shown in FIG. 14. In some cases, the edgesmay sustain damage during stacking and transporting. Accordingly, thisembodiment is well-suited to prevent such damage. In the other preferredembodiment, shown in FIG. 1, the inserts 34 are on the inside of thecontainer 10 and do not overlap the rest of the wall 12.

Additionally, the inner blank 30, the outer blank 32, and at least oneof the inserts 34 preferably has a hole 24 near the bottom 18 to createthe drain hole 24 in the container wall 12, and each of these holes 24are aligned in the assembled container 10.

One preferred method of manufacturing the container 10 utilizes twofour-panel 36 blanks 30,32 and two two-panel 36 inserts 34, as describedabove, and is illustrated in FIGS. 7-10. This method may be used tocreate the container 10 illustrated in FIGS. 1-6 and 11 -13. The outerblank 32 has four fold lines 14 creating four panels 36 and a connectingflap 38, and the inner blank 30 has three fold lines 14 creating fourpanels 36, as shown in FIGS. 8 and 9. The outer blank 32 and the innerblank 30 are attached together in an offset manner as shown in FIG. 8.The first insert 34 is then attached to the surface of the inner blank30 so that the single-scored fold line 14 of the insert 34 is alignedwith the single scored fold line 14 of the inner blank. In thisarrangement, the two panels 36 of the first insert 34 cover two of thepanels 36 of the inner blank 30, leaving two other panels 36 of theinner blank 30 uncovered, illustrated in FIG. 10. Preferably, thecoverage of the insert 34 extends from one double-scored fold line 14 tothe other double-scored fold line 14, but does not cover either of thetwo double-scored fold lines 14, as described above.

After the first insert 34 has been attached to the inner blank 30, thesecond insert 34 is lain on the first insert 34, preferably flipped over(180°), as shown in FIG. 10. The two free, uncovered panels 36 of theinner blank 30 are then folded inward to cover the second insert 34,thereby attaching the inner blank 30 to the second insert 34. The outerblank 32 is also folded inward during this step, since it is attached tothe inner blank 30, and the connecting flap 38 overlaps, and is attachedto, a portion of the inner blank 30. Completion of this step forms aflattened container 10, as described above, having four walls 12 (two onthe top side, two on the underside) with four fold lines 14, as shown inFIGS. 5 and 11. Two of the fold lines 14 are at the edges of theflattened container 10, folded at substantially 0° angles, and the othertwo fold lines 14 are proximate the middle of the flattened container10, unfolded to substantially 180° angles. Finally, the bulk container10 is formed by folding the four fold lines 14 to an angle of 90° toform a four-walled rectangular container 10, shown in FIGS. 1-3. Thecontainer 10 is shown in a partially-collapsed state in FIG. 6, toillustrate how the container 10 folds and unfolds between expanded andcollapsed states. Preferably, the three fold lines 14 of the inner blank30 and the fold line 14 of the connecting flap 38 form the four corners28 of the assembled container 10.

The most preferred method of manufacturing the container 10 of thepresent invention is illustrated in FIGS. 19-21, and utilizes fourtwo-panel 36 blanks (two inner 30 and two outer blanks 32) and twotwo-panel 36 inserts 34, as described above. This method may be used tocreate the container 10 illustrated in FIGS. 14-18. Each outer blank 32has two fold lines 14 creating two panels 36 and a connecting flap 38,and each inner blank 30 has one fold line 14 creating two panels 36, asshown in FIGS. 19-20. Each outer blank 32 is attached to one of theinner blanks 30 in an offset manner as shown in FIG. 19. Each insert 34is then attached to the outer surface of one of the outer blanks 32 sothat the single-scored fold line 14 of the insert 34 is aligned with thesingle-scored fold line 14 at the connecting flap 38. In thisarrangement, one panel 36 of the insert 34 covers one panel 36 of theouter blank 32, while the other panel 36 of the insert 34 covers onlythe connecting flap 38, with a portion 52 of the insert 34 extendingpast the outer edge of both the inner 30 and outer blanks 32, as shownin FIG. 21. Preferably, the coverage of the insert 34 extends to thedouble-scored fold line 14 of each blank, but does not cover thedouble-scored fold line 14, as described above.

After this step, two identical half-containers 11 have been created,each containing one inner blank 30, one outer blank 32, and one insert34. One such half-container 11 is depicted in FIG. 21. The final step inmanufacturing is to connect the two half-containers 11 together to forma full container 10, as illustrated in FIG. 18. In this connection, theconnecting flap 38 of the outer blank 32 of each half-container 11attaches to the overlapping portion 39 of the inner blank 30 of theother half-container 11, and the overlapping portion 50 of the insert 34of each half-container 11 connects to the uncovered panel 36 of theouter blank 32 of the other half-container 11. Preferably, the twodouble-scored fold lines 14 and the two single scored fold lines 14adjacent the connecting flaps 38 form the four corners 28 of theassembled container 10. This assembled container 10 collapses andexpands as described above, and illustrated in FIGS. 16 and 17.

In the preferred methods of manufacturing the bulk container 10, theblanks 30,32 and inserts 34 are attached together by laminating withglue or other adhesive 44. However, many other suitable means ofattaching such structures together are known in the art, and can be usedwith the disclosed method. Further, the most effective means ofattachment can vary, if a different material is used for the blanks30,32 and inserts 34.

The present method also preferably includes scoring the blanks 30,32 andinserts 34, preferably by die-cutting straight lines 26 in the surfaceof the cardboard with a scoring tool. This tool causes deep compressionin the walls 12 along the score lines 26. In multi-ply walls 12, thescoring preferably extends through each ply of the walls 12, as shown inFIGS. 4, 12, 15, and 17. Any other known scoring method is suitable foruse in the disclosed method, including blade-cutting or pressing. Asdiscussed above, one preferred inner blank 30 has three scored foldlines 14, as shown in FIGS. 9-10. Two of the fold lines 14 aredouble-scored, i.e., having a set of two parallel score lines 26 on thesurface of the blank 30. A third fold line 14, preferably locatedbetween the first and second fold lines 14, is single-scored, havingonly a single score line 26. The corresponding outer blank 32 has thesame three scored fold lines 14 as the inner blank, but contains anadditional single-scored fold line 14 at the connecting flap 38, asshown in FIG. 10. In the most preferred embodiment, each inner blank 30has one double-scored fold line 14, and each outer blank 32 has onedouble-scored fold line 14 and an additional single-scored fold line 14at the connecting flap 38, as described above and illustrated in FIG.20.

Each insert 34 preferably has a single fold line 14 that issingle-scored, also illustrated in FIG. 10. Preferably, all score lines26 are straight and parallel to their respective fold lines 14, howeverother score line 26 configurations may be used with the presentcontainer 10. Scoring can be done at any point during the manufacturingprocess. In the most preferred method, the blanks 30,32 and inserts 34are scored prior to assembly, and measured carefully to ensure the scorelines 26 will all be aligned properly when assembled. In otherembodiments, the blanks 30,32 and inserts 34 are scored after assemblyor at some point during the assembly process.

The disclosed method can be modified without departing from the scope ofthe present invention. Most importantly, the present inventioncontemplates the addition of other steps and components to the method.For example, although the preferred method calls for the use of twoblanks 30,32 and two inserts 34, additional blanks 30,32 and/or inserts34 can be used. Also, the method can incorporate differently-sizedblanks 30,32 and inserts 34. Indeed, since the disclosed method isuseful in manufacturing containers having shapes other than rectangular,the use of other blanks 30,32 or inserts 34 is desirable in manyembodiments. One skilled in the art would understand how to attach andscore these additional blanks 30,32 and inserts 34 in keeping with thedisclosed method. Similarly, additional or fewer folding or scoringsteps are used in some embodiments, particularly in containers ofdifferent shapes and if a different size or number of blanks 30,32 orinserts 34 are used. In another embodiment, the flaps 20 are separateand must be attached to the container 10 as well.

The disclosed container is particularly useful for handling liquids orother flowable materials contained in an impermeable bag held within thecontainer. Most advantageously, the bag is held within a cardboardcartridge configured to sit at the bottom of the container when the bagis filled, covering the open bottom. Such bags, when filled, often weigharound 2000 lb. The open top allows for the bag to be filled and thedrain hole allows for draining liquid from the bag, preferably through adrain spout. The strength created by the eight-ply corrugated cardboardwalls of the container increase the vertical compressive strength of thecontainer, maximizing stacking height. The added strength also helps toprotect and support the bag contained within.

A chief benefit of the disclosed container is the ease of collapsing,stacking, and storing the container. The score lines allow thecontainer, despite having thick, sturdy walls, to collapse to aflattened shape having a minimum possible thickness with no gaps betweenthe material. This collapsed container 10 is shown in FIG. 6. Onceflattened, the container can be stably stacked with other collapsedcontainers for easy, compact storage and transporting. When needed, thecollapsed container is quickly and readily expandable to its workingform.

The terms “first,” “second,” “third,” “fourth,” etc., as used herein areintended for illustrative purposes only and do not limit the embodimentsin any way. Further, the term “plurality” as used herein indicates anynumber greater than one, either disjunctively or conjunctively, asnecessary, up to an infinite number.

While the specific embodiments have been illustrated and described,numerous modifications come to mind without significantly departing fromthe spirit of the invention, and the scope of protection is only limitedby the scope of the accompanying claims.

1. A bulk container comprising: a plurality of substantially planarwalls; a plurality of corners, each corner connecting two walls, whereina first corner and a second corner opposite the first corner each havetwo substantially parallel score lines on an inner side allowing thefirst and second corners to fold at an angle of substantially 0° whilemaintaining the structural integrity of the container; a top formed by aplurality of foldable flaps; and a bottom formed by a plurality offoldable flaps.
 2. The bulk container of claim 1 wherein the walls arecomprised of at least first and second three-ply corrugated cardboardblanks and at least first and second two-ply corrugated cardboardinserts, wherein the inserts do not overlap each other.
 3. The bulkcontainer of claim 2, wherein the walls are further comprised of atleast third and fourth three-ply corrugated cardboard blanks.
 4. Thebulk container of claim 3, wherein the inserts are located on aninterior of the container.
 5. The bulk container of claim 3, wherein theinserts are located on an exterior of the container.
 6. The bulkcontainer of claim 1, wherein a third inner corner and a fourth innercorner each have a score line allowing each of the third and fourthcorners to fold at an angle of at least 90° while maintaining thestructural integrity of the container.
 7. The bulk container of claim 1,wherein each wall is formed of at least eight-ply corrugated cardboardsheet.
 8. A bulk container comprising: a multi-ply corrugated cardboardsleeve comprised of a first layer of multi-ply corrugated cardboardlaminated to a second layer of multi-ply corrugated cardboard, thesleeve folded to form a plurality of walls and a plurality of cornersdefining a perimeter; a first corrugated cardboard insert comprising afoldable top flap and a foldable bottom flap and laminated to a surfaceof the sleeve, the first insert extending approximately half theperimeter; and a second corrugated cardboard insert comprising afoldable top flap and a foldable bottom flap and laminated to a surfaceof the sleeve, the second insert extending approximately half theperimeter and separate from the first insert, wherein the top flaps foldinward to form a top of the container and the bottom flaps fold inwardto form a bottom of the container.
 9. The bulk container of claim 8,wherein the first and second inserts are laminated to an interiorsurface of the sleeve.
 10. The bulk container of claim 8, wherein thefirst and second inserts are laminated to an exterior surface of thesleeve.
 11. The bulk container of claim 8, wherein a first corner and asecond corner opposite the first corner each have two substantiallyparallel score lines on an inner side allowing the first and secondcorners to fold at an angle of substantially 0° while maintaining thestructural integrity of the container.
 12. The bulk container of claim11, wherein a third corner and a fourth corner each have a score lineallowing each of the third corner and the fourth corner to fold at anangle of at least 90° while maintaining the structural integrity of thecontainer.
 13. A method of constructing a bulk container having a top, abottom, and a plurality of walls, comprising the steps of: providing afirst blank comprising a first panel and a second panel separated by afirst fold line comprising a pair of substantially parallel score lines;providing a second blank comprising a first panel and a second panelseparated by a first fold line comprising a pair of substantiallyparallel score lines; attaching a surface of the first blank to asurface of the second blank such that the fold line of the first blankis substantially aligned with the fold line of the second blank;providing a first insert comprising a top flap, a bottom flap, and afirst panel and a second panel separated by a fold line; attaching asurface of the first insert to a surface of the second blank such thatthe first panel of the first insert is substantially aligned with one ofthe first panel and the second panel of the second blank; and foldingthe first blank, the second blank, and the first insert at the foldlines to create a number of the walls of the bulk container.
 14. Themethod of claim 13, further comprising the steps of: providing a thirdblank comprising a first panel and a second panel separated by a foldline comprising a pair of substantially parallel score lines; providinga fourth blank comprising a first panel and a second panel separated bya fold line comprising a pair of substantially parallel score lines;attaching a surface of the third blank to a surface of the fourth blanksuch that the fold line of the third blank is substantially aligned withthe fold line of the fourth blank; providing a second insert comprisinga top flap, a bottom flap, and a first panel and a second panelseparated by a fold line; attaching a surface of the second insert to asurface of the fourth blank such that the first panel of the secondinsert is substantially aligned with the first panel of the fourthblank; folding the third blank, the fourth blank, and the second insertat the fold lines to create a number of the walls of the bulk container;and attaching the number of walls created by the first blank, the secondblank, and the first insert to the number of walls created by the thirdblank, the fourth blank, and the second insert to create four walls andfour substantially 90° corners of the bulk container.
 15. The method ofclaim 13, wherein the first blank further comprises a third panel,separated from the second panel by a second fold line comprising a scoreline, and a fourth panel, separated from the third panel by a third foldline comprising a pair of substantially parallel score lines, and thesecond blank further comprises a third panel, separated from the secondpanel by a second fold line comprising a score line, and a fourth panel,separated from the third panel by a third fold line comprising a pair ofsubstantially parallel score lines, further comprising the steps of:attaching a surface of the first blank to a surface of the second blanksuch that the first fold line of the first blank is substantiallyaligned with the first fold line of the second blank, the second foldline of the first blank is substantially aligned with the second foldline of the second blank, and the third fold line of the first blank issubstantially aligned with the third fold line of the second blank;providing a second insert comprising a top flap, a bottom flap, and afirst panel and a second panel separated by a fold line; attaching asurface of the second insert to a surface of the second blank such thatthe first panel of the second insert is substantially aligned with oneof the third panel and the fourth panel of the second blank; and foldingthe first blank, the second blank, the first insert, and the secondinsert at the fold lines to create four walls and four substantially 90°corners of the bulk container.
 16. The method of claim 13, wherein thepair of substantially parallel score lines allow the first blank and thesecond blank to fold at substantially a 180° angle while maintaining thestructural integrity of the container.
 17. The method of claim 13,wherein the first blank is comprised of three-ply corrugated cardboard,the second blank is comprised of three-ply corrugated cardboard, and theinsert is comprised of two-ply corrugated cardboard.
 18. The method ofclaim 13, wherein the second blank further comprises a second fold linecreating a connecting flap, and the first blank and the second blank areattached in an offset manner, allowing the connecting flap to fold atthe second fold line.
 19. The method of claim 13, wherein the firstblank, the second blank, and the first insert are folded such that thefirst insert is located on an exterior of the bulk container.
 20. Themethod of claim 13, wherein the first blank, the second blank, and thefirst insert are attached by laminating with an adhesive.